1. Field of the Invention
The present invention relates to a solution supplying device, for example, to a solution supplying device for supplying a process solution for a photographic material such as silver halide used in an automatic developing device.
2. Description of the Related Art
After a photographic material such as silver halide is exposed, a developing process is performed using process solutions such as a developing solution, a bleaching solution, and a fixing solution. Generally, in the developing process, an automatic developing device is used. When necessary, to keep each process solution active and the composition thereof constant, those process solutions are replenished. Each process solution is supplied as a concentrated solution comprised of a plurality of part solutions. Thus, when each process solution is used, it should be diluted and compensated with water for a predetermined concentration. However, since each process solution should be accurately diluted, a very laborious work is required so as to prevent the process solution from being improperly dissolved and contaminated with another process solution. In addition, when each process solution is compensated, it tends to splash, thereby dirty the human body, cloths, and peripheral devices.
To solve such problem, many prior art references have been proposed. For example, according to one prior art reference, a sucking nozzle is connected to a supplying vessel that packs a process solution so that an undiluted process solution is supplied to a process tank of an automatic developing device. In addition, a predetermined amount of water is supplied from a different diluting water stock tank to the process tank. As a result, the process solution is replenished without need to compensate it.
In particular, according to a prior art reference disclosed as Japanese Patent Laid open Publication No. 2000-2995, a flexible vessel is used. When the amount of an undiluted process solution decreases in the flexible vessel, the undiluted process solution can be prevented from contacting air. In addition, a solution empty state detecting device is disposed. The solution empty state detecting device detects the expansion of a gas that flows from the vessel to a solution supplying pump so as to determine that the solution contained in the vessel has run out. That replenishing method has excellent features of which an undiluted process solution is stable and the vessel can be easily replaced with a new one.
However, in the method according to the above-described related art reference, when an amount of air that exceeds the predetermined value enters a flow path, the solution empty state detecting device will malfunction. Thus, when an undiluted process solution is enclosed in a vessel as a product, the amount of air that enters the vessel should be strictly controlled. In addition, even if the amount of air that enters the vessel is strictly controlled, when a solution that is packed in the vessel for a long time produces a gas, since the amount of the gas that enters the flow path may exceed a predetermined value, such a method cannot be used.
In addition, as there are many types of output services due to an explosive increase of demands of silver salt prints of digital mediums, non-photograph shops tend to start DPE (Developing, Printing, and Enlarging) services. Thus, there are strong demands for an automatic developing device that does not need a large installation space, that does not need an experienced operator, and that does not need a full-time intervention of an operator.
In the replenishing device according to the related art reference, although the device can be operated easily, the structures of the solution supplying portion and the solution empty state detecting portion are complicated. Thus, it is difficult to reduce the sizes of those portions. Consequently, the replenishing device according to the related art reference is disadvantageous for a small automatic developing device. In addition, the size of the replenishing device according to the related art reference need to become large in proportion to the volume of a vessel connected thereto. Thus, the replenishing device according to the related art reference does not satisfy the needs for providing a vessel having a large volume that reduces the frequency of which the vessel is replaced. In addition, when the solution contained in the vessel has run out, unless it is replaced with a new one, the developing process cannot be continued. Thus, the automatic developing device always requires the intervention of an operator.
An object of the present invention is to provide an improved solution supplying device that allows an undiluted process solution to be stable, a vessel that packs the solution to be easily replaced, and a large amount of gas that enters a flow path to be prevented from malfunctioning. Another object of the present invention is to provide a solution supplying device that satisfies both needs for reducing the size of a solution supplying portion and the labor of the operator.
To accomplish such objects, an aspect of the present invention is a device for temporarily stocking a solution supplied from a vessel that packs the solution and supplying the solution to a destination, comprising a stock tank for stocking the solution supplied from the vessel, a solution supplying pump for supplying the solution stocked in the stock tank to the destination, and a pressure varying portion for varying the inner pressure of the stock tank.
According to the aspect of the present invention, when a pressure varying portion is disposed, since a small solution supplying pump can be used without a problem for supplying a solution, a device such as an automatic developing device can be compactly structured. When the solution is supplied from a vessel to a destination through a stock tank by the solution supplying pump, if the solution packed in the vessel has run out, an excessively reduced pressure state takes place in the stock tank. At a particular point, the sucking force of the solution supplying pump is balanced with the inner pressure of the stock tank, leading to a state that the solution stocked in the stock tank can no longer be sucked. However, according to the present invention, since the pressure varying portion is operated before such a suction disable state takes place, the excessively reduced pressure state can dissolve in the stock tank. Thus, the solution can be supplied continuously from the stock tank to the destination by the solution supplying pump. In other words, with the pressure varying portion, even if the power of the solution supplying pump is not large, the solution can be continuously supplied without an abnormality of the operation of the solution supplying pump.
The pressure varying portion is a valve disposed on the stock tank and opened so that outside air enters the stock tank when the inner pressure of the stock tank is a predetermined value or less. Thus, as the pressure varying portion, a valve can be used so that it opens and outside air enters the stock tank when the inner pressure of the stock tank is a predetermined value or less. In such a structure, when the valve is opened, the excessively reduced pressure state can dissolve in the stock tank. Alternatively, an orifice may be used instead of the valve. Thus, when the orifice is used, the excessively reduced pressure state can dissolve in the stock tank, by using a very simple structure and at very low cost.
The pressure varying portion is a volume varying chamber, disposed at a part of the stock tank, for varying the inner volume so as to vary the inner pressure. Thus, as a pressure varying portion, a volume varying chamber can be disposed. The volume varying chamber is structured in such a manner that the inner volume is large in the normal state, whereas the inner volume is small in the excessively reduced pressure state. Thus, when the inner volume of the volume varying chamber decreases, the excessively reduced pressure state can dissolve in the stock tank.
The inner volume of the volume varying chamber is decreased when the inner pressure of the stock tank is a predetermined value or less. In such a structure, when the inner volume of the volume varying chamber is decreased, the excessively reduced pressure state can dissolve in the stock tank.
The device further comprises a gas exhausting mechanism for exhausting a gas from a flow path for the solution, the flow path being formed from the vessel to the solution supplying pump. In such a structure, even if an unexpected amount of air enters a flow path, the solution empty state detecting device does not malfunction. Thus, when a solution is packed to a vessel as a product, it is not necessary to strictly control the amount of air that enters the vessel. In addition, even if a solution that has been stocked for a long time produces a gas, the solution can be used. In other words, when a gas is sucked to the flow path, the gas quickly separates from the solution in the stock tank. The gas gathers at an upper portion of the stock tank. When the amount of the gas exceeds a predetermined value, a gas exhausting mechanism exhausts the gas to the outside. Thus, even if an unexpected amount of gas enters the flow path, the gas can be exhausted to the outside thereof.
The gas exhausting mechanism has an exhausting pipe connected to the stock tank, an air pump, connected to the exhausting pipe, for exhausting a gas from the stock tank through the exhausting pipe, and a flow rate adjusting mechanism for adjusting the flow rate of the gas exhausted by the air pump. As a gas exhausting mechanism, an exhausting pipe and an air pump can be used.
The flow rate adjusting mechanism is composed of a plurality of pipes that have different diameters and that are connected. In such a structure, when a pipe has portions that are different in thickness and length, the flow rate of an exhaust gas can be adjusted to a predetermined value. When a pump having a larger flow rate than a desired exhaust flow rate is used, since the exhaust flow rate is too large, the solution may reversely flow in the air pump. However, when the pipe is partly narrowed, since a flow rate loss actively takes place, the exhaust flow rate of the gas can be adjusted.
A sensor for detecting a predetermined solution level of the solution is disposed in the stock tank. The operation of the air pump is controlled corresponding to a detected result of the sensor. In such a structure, an air pump is interlocked with a sensor that detects a solution level. With a time relay or the like, the air pump is stopped after a predetermined time period elapses. Thus, a gas in the stock tank can be exhausted effectively. In addition, since only one sensor for controlling the air pump is used, a device such as an automatic developing device can be structured compactly.
The sensor has a first sensor, disposed in the stock tank, for detecting a predetermined solution level of the solution, and a second sensor, disposed at a higher position than the first sensor in the stock tank, for detecting a predetermined solution level of the solution. The air pump is started corresponding to a detected result of the first sensor and is stopped corresponding to a detected result of the second sensor. Thus, with two sensors, a gas that enters the stock tank can be more accurately exhausted. When only one sensor is used, it tends to chatter. Thus, the service lives of the sensors can be prolonged.
A solution empty state detecting sensor is further disposed in the stock tank. In such a structure, a sensor detects a solution empty state in a vessel while a stock tank stores the solution. Thus, even if the solution of the vessel has run out, the process can be performed with the solution stocked in the stock tank. Consequently, unlike the conventional device, it is not necessary to replace the vessel just after the solution of the vessel has run out providing extra time before the replacing. Thus, since the operator does not need to always supervise the solution supplying device because of the extra time allowed in changing the vessel, the labor of the operator for the intervention of the automatic developing device can be reduced.
A solution empty state detecting sensor for detecting that the solution stocked in the stock tank runs out is further disposed. In such a structure, a solution empty state detecting sensor is disposed in the stock tank so that the sensor detects the solution empty state of the solution in the stock tank before the solution of the stock tank has run out. Thus, corresponding to the detected result of the sensor, the solution supplying pump and the solution supplying device can be stopped. Thus, when the solution has run out in both the stock tank and the vessel, the solution supplying pump is not operated. Consequently, air does not enter the solution supplying pump. As a result, the solution can be accurately supplied.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of a best mode embodiment thereof, as illustrated in the accompanying drawings.